1. Field of the Invention
The invention generally relates to the technique of carrier aggregation, and more particularly, to wireless apparatuses, wireless systems, and methods for managing the activation and deactivation of multiple component carriers.
2. Description of the Related Art
In order to meet users' demand for higher data rate in wireless communications, support of wider transmission bandwidths is required. A so-called Carrier Aggregation (CA) technique has been proposed to allow expansion of effective bandwidth delivered to a user terminal through concurrent utilization of radio resources across multiple carriers. The CA technique is most useful when it is difficult to derive a contiguous and extra wide bandwidth. With the CA technique, more than 2 frequency bands may be aggregated to form a larger transmission/receive bandwidth. Each of the aggregated frequency channels is generally referred to as a Component Carrier (CC), which may be taken as a component of the aggregated bandwidth.
Specifically, a CC needs to be configured and activated before it may be used for data transmission or reception. Taking a Long Term Evolution (LTE) technology as an example, an LTE system may first transmit a Radio Resource Control (RRC) message to configure the CCs for the user terminal, and then activate the CCs by dedicated signaling, such as a Medium Access Control (MAC) Control Element (CE). Later, if a smaller transmission bandwidth is required instead, the LTE system may transmit another MAC CE to the user terminal to deactivate one of the activated CCs. Alternatively, a deactivation timer (or may be referred to as a release timer) may be maintained both in the network side and/or the user terminal to count a predetermined time period when the corresponding activated CCs may stay activated. When the deactivation timer expires, the LTE system and/or the user terminal may deactivate the corresponding CCs. Since the user terminal does not need to monitor the physical downlink shared channel (PDSCH) and physical downlink control channel (PDCCH) corresponding to the deactivated CCs, power consumption of the user terminal may be efficiently reduced.